Friday, January 30, 2015

Here is a good, handy online version of the TrimTeck globe control valve catalog. Its full of excellent control valve selection criteria and is illustrated quite well, showing body styles, packing styles, bonnet design, flow paths, end connections, and seat designs.

Thursday, January 29, 2015

Annunciators are found in industrial control rooms, boiler rooms, power substations and just about any type of process control operations room where the process conditions need to be closely monitored and where constant status indication is important.

Here is an outline for the primary selection criteria for an integrated logic alarm annunciator:

Chassis

Panel mount

Surface mount

Rack mount

Alarm Points

How many alarm points do you have? Annunciators break down alarm points by "cell" and you call out the number of cells based on the layout desired. For instance, a 1x4 would be 1 annunciator cell tall by 4 cells wide.

Pushbuttons (and Location)

Occupying bottom right
module cell space

On the bottom right trim of the chassis

Located remotely

The Available Panel, Box or Cabinet Space Available

Dictates how alarm points and pushbuttons are arranged.

Networkable or Stand-alone?

Configuration via software?

Event recording?

Do you need electrical outputs?

Audible and visual signals: horn, beacon, bell

Common Trouble Alarm (CTA) Relay: notification of any alarm within the system (commonly used
for remote beacon or dial-up)

VA meters are an inexpensive flow-metering device available for a variety of industrial applications. VA meters with indicator only are still the norm; however, more VA meters are being specified with options such as flow alarms and analog output transmitters. This

is happening for a couple of reasons. Monitoring a process remotely provides better control because the entire flow line can be monitored. Using a VA meter with an analog output transmitter allows one person to monitor several process lines remotely.

Another technique for monitoring a flow line is a VA meter with a flow switch. The switch can be set to trigger at a given flow rate. When the flow rate reaches the set point, a signal could cause a valve to close or open. A pump could be turned on or off or a simple light or some other signal could be activated.

The other major trend in VA meters is the transition from glass tube rotameters to metal tube rotameters. Metal tube meters are more durable and require less maintenance. Plus, if a glass tube breaks, not only is there the expense of the glass tube, there is downtime and maintenance technician time to consider, too.

Unlike other flow meters, VA meters will respond like a canary in a coal mine when air quality changes. If process conditions change, they usually impact flow rate. For example, if the back pressure changes on gas flows, the flow rate will change. For this reason, it’s necessary for engineers to take several factors into consideration when specifying a VA meter for their applications:

Wednesday, January 21, 2015

High-temperature refractory metallization is the only solution for some packaging applications. Tungsten and Moly-Manganese metallizations have higher adhesion to the substrate than thick-film metallization. This makes it the ideal process for hermetic packages, brazed lead frames and packages requiring high operating temperatures. These metals can be screen printed, sprayed or hand-painted onto alumina oxide or beryllium oxide substrates. Patterns can be plated with gold and nickel or gold alone. Once gold plated, these surfaces are solder-able and wire bond-able with aluminum or gold wire.

Batch furnaces are ideal for accurate brazing of small quantities and large. Kovar, stainless steel, copper and copper/tungsten as well as many other metals can be brazed to metallized ceramic. When the application requires, step brazing can be performed to combine several sub-assemblies into the final product.

For more information on hi-temperature refractory metallization contact:

Thermocouple "Types", based upon standardized color designations is discussed, as well as thermocouple connectors, polarity and some aspects of construction (such as grounded vs. ungrounded vs. open tip).

Thermocouples are a fairly accurate, economic temperature sensor used in many industrial applications. They operate on the "Seebeck Effect" which is the phenomena of dissimilar metal conductors producing a measurable voltage difference between two substances.

Thermocouples are used widely in industrial thermal system design in industries such as power generation, primary metals, pulp and paper, petro-chemical, and OEM equipment.

Sunday, January 4, 2015

Thick filmheating elements, originally designed for the automotive and military industries, are manufactured by depositing several layers of conductor, resistors and dielectric on to an insulator via a screen printing process. The dielectric is normally some type of glass or ceramic and provides electrical insulation for the screen printed heating tracks.

Thick film heating elements are almost always custom designed for OEM applications. They can be designed in all shapes and sizes, and have an ability to provide very high watt densities with excellent controllability. The largest markets for these heating elements are appliances, analytical instruments, automotive, semi-conductor, medical device, scientific and military equipment.

Because of their inherent low mass, and their ability to carry high watt densities, thick film heaters are very efficient and are an excellent choice where a rapid heat-up (response) is required.